Department of Community Health and Epidemiology, Nara Medical University School of Medicine, Japan.
Kashihara Kenko Sports Club, Nara, Japan.
J Gerontol A Biol Sci Med Sci. 2016 Sep;71(9):1235-40. doi: 10.1093/gerona/glw030. Epub 2016 Mar 1.
Decreased muscle strength is associated with functional limitation and disability and is a predictor of cardiovascular and all-cause mortality. Recently, oxidative stress and inflammation have been shown to contribute to the loss of muscle strength, and although melatonin has antioxidative and anti-inflammatory properties, the association between melatonin secretion and muscle strength remains unclear.
In this cross-sectional study of 760 community-based elderly individuals (mean age, 71.0 years), we measured overnight urinary 6-sulfatoxymelatonin excretion (UME) and grip strength and quadriceps strength.
Median UME was 7.0 μg (interquartile range, 4.2-11.1), and mean grip and quadriceps strength were 27.5±8.4kg and 162.6±80.1 Nm, respectively. On dividing participants into quartiles by their UME level (lowest-highest UME, Q1-Q4), higher quartiles were significantly associated with increased grip strength and quadriceps strength (p for trend < .001, both). Multivariable analyses adjusted for potential confounders (age, gender, body mass index, smoking and drinking statuses, renal function, hypertension, diabetes, physical activity, depressed mood, cognitive impairment, bedtime, sleep duration, and day length) revealed that both grip and quadriceps strength were significantly increased in Q4 compared with that in Q1 (adjusted mean difference, Q4 - Q1: grip strength, 1.5kg; 95% confidence interval [CI], 0.4-2.6kg; p = .006; quadriceps strength, 14.2 Nm; 95% CI, 1.3-27.1 Nm; p = .031).
Melatonin secretion was significantly associated with muscle strength in this elderly population. Further longitudinal studies are needed to ascertain the effect of melatonin levels on muscle strength.
肌肉力量下降与功能受限和残疾有关，是心血管疾病和全因死亡率的预测指标。最近，氧化应激和炎症被证明与肌肉力量的丧失有关，尽管褪黑素具有抗氧化和抗炎作用，但褪黑素分泌与肌肉力量之间的关系尚不清楚。
在这项针对 760 名社区老年人的横断面研究中（平均年龄 71.0 岁），我们测量了夜间尿液 6-硫酸褪黑素排泄量（UME）和握力以及股四头肌力量。
UME 的中位数为 7.0μg（四分位间距，4.2-11.1），平均握力和股四头肌力量分别为 27.5±8.4kg 和 162.6±80.1Nm。将参与者按 UME 水平分为四分位数（UME 最低-最高 Q1-Q4），较高的四分位数与握力和股四头肌力量的增加显著相关（趋势检验 p<0.001，两者均）。经调整潜在混杂因素（年龄、性别、体重指数、吸烟和饮酒状况、肾功能、高血压、糖尿病、身体活动、抑郁情绪、认知障碍、就寝时间、睡眠时间和昼长）的多变量分析显示，与 Q1 相比，Q4 的握力和股四头肌力量均显著增加（调整后的平均差异，Q4-Q1：握力，1.5kg；95%置信区间[CI]，0.4-2.6kg；p=0.006；股四头肌力量，14.2Nm；95%CI，1.3-27.1Nm；p=0.031）。
在本老年人群中，褪黑素分泌与肌肉力量显著相关。需要进一步的纵向研究来确定褪黑素水平对肌肉力量的影响。
